Producing wells often use a down-hole pump for pumping substances to the surface. These down-hole pumps can comprise a plunger pump or “sucker rod” pump operated by pump jacks, as well known to those skilled in the art.
A linear motor has its stator and rotor in linear motion that produces a linear force along its length. Electrical energy is converted directly into mechanical energy by the motor, with the linear reciprocating up and down motion of the motor being used to directly pump oil. Such typical linear motors are powered by direct current (“DC”) power. Alternating current (“AC”) powered linear motors, however, have not been used with any degree of success in operating down-hole pumps.
It is, therefore, desirable to provide a controller for controlling an AC-powered linear motor that can effectively and efficiently operate a down-hole pump for pumping substances from a well to the surface.